Gold Karat Converter
How much weight of one karat is equivalent to another karat by pure gold content. Useful when comparing jewelry across markets or negotiating a trade-in.
That same pure gold content is equivalent to the weights below in other karats:
How the conversion works
The key insight is that karat describes purity, not weight. Every karat is a different percentage of pure gold mixed with base metals. To convert a piece of one karat to its equivalent weight in another karat, we calculate the pure gold content of the original and then compute how much of the target karat alloy would contain the same pure gold.
The formula is simple:
Target weight = Source weight × (Source purity ÷ Target purity)
For example: 10 grams of 22K gold contains 10 × 0.9167 = 9.167 grams of pure gold. To get the same 9.167 grams of pure gold from 18K alloy, which is 75% pure, you would need 9.167 ÷ 0.75 = 12.22 grams of 18K. So 10g of 22K = 12.22g of 18K by pure gold content.
When this matters in practice
Jewelry trade-ins. If you bring in a 22K bangle and want to exchange it for 18K pieces (common when moving from Indian to European-style jewelry), the jeweler should credit you with the pure gold content of your piece and charge you for the pure gold content of the new one, adjusted for making charges. Knowing the karat-equivalent weight lets you check the math.
Cross-border comparisons. Comparing "price per gram" between a 22K bangle in Mumbai and a 14K chain in Los Angeles is meaningless. Convert both to pure-gold equivalent first, then compare.
Refining and melting. Refiners quote yields in pure gold, not alloy weight. A quote for "15 grams recoverable" from a 20-gram 18K piece is consistent with the 75% purity; a quote for only 12 grams would be flagging a shortfall.
The karats we cover
Every purity from 8K through pure 24K, plus the two standard fine grades used in modern bullion coins:
- 8K — 33.3% pure (333 stamp). Rare in jewelry, more common in costume pieces.
- 9K — 37.5% pure (375 stamp). Standard in the UK for affordable jewelry.
- 10K — 41.7% pure (417 stamp). Legal minimum to be sold as "gold" in the United States.
- 12K — 50% pure (500 stamp). Uncommon; occasionally seen in vintage pieces.
- 14K — 58.3% pure (585 stamp). North American standard.
- 18K — 75% pure (750 stamp). European fine-jewelry standard.
- 20K — 83.3% pure (833 stamp). Rare standard, occasionally seen in Southeast Asia.
- 21K — 87.5% pure (875 stamp). Saudi Arabia and Gulf states.
- 22K — 91.67% pure (916 stamp). Indian subcontinent standard.
- 23K — 95.8% pure (958 stamp). Occasionally seen in high-purity bridal pieces.
- 24K — 99.9% pure (999 stamp). Asian investment jewelry and bullion.
- 9999 fine — 99.99% pure. Modern bullion coin standard (Canadian Maple, American Buffalo, etc.).
Further tools
- Melt value calculator — put in a weight and karat, get the gold value
- Unit converter — gram ↔ troy ounce ↔ tola ↔ tael
- Coin calculator — live melt value for famous coins
- Read: gold karat systems around the world